/*-------------------------------------------------------------------------
 *
 * be-pqexec.c--
 *    support for executing POSTGRES commands and functions from a
 *    user-defined function in a backend.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /usr/local/cvsroot/postgres95/src/backend/libpq/be-pqexec.c,v 1.2 1996/11/06 08:48:26 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */
/*
 * INTERFACE ROUTINES
 * 	PQfn 		- call a POSTGRES function
 * 	PQexec 		- execute a POSTGRES query
 *	
 * NOTES
 *	These routines are compiled into the postgres backend.
 */
#include <postgres.h>

#include <nodes/pg_list.h>
#include <tcop/dest.h>
#include <tcop/fastpath.h>
#include <tcop/tcopprot.h>
#include <lib/dllist.h>
#include <libpq/libpq-be.h>
#include <fmgr.h>
#include <utils/exc.h>
#include <utils/builtins.h>
#ifndef HAVE_MEMMOVE
# include <regex/utils.h>
#else
# include <string.h>
#endif

/* ----------------------------------------------------------------
 *			PQ interface routines
 * ----------------------------------------------------------------
 */

/* ----------------
 *	PQfn -  Send a function call to the POSTGRES backend.
 *
 *	fnid		: function id
 * 	result_buf      : pointer to result buffer (&int if integer)
 * 	result_len	: length of return value.
 * 	result_is_int	: If the result is an integer, this must be non-zero
 * 	args		: pointer to a NULL terminated arg array.
 *			  (length, if integer, and result-pointer)
 * 	nargs		: # of arguments in args array.
 *
 *	This code scavanged from HandleFunctionRequest() in tcop/fastpath.h
 * ----------------
 */
char *
PQfn(int fnid,
     int *result_buf,		/* can't use void, dec compiler barfs */
     int result_len,
     int result_is_int,
     PQArgBlock *args,
     int nargs)
{
    char *retval;		/* XXX - should be datum, maybe ? */
    char *arg[8];
    int  i;
    
    /* ----------------
     *	fill args[] array
     * ----------------
     */
    for (i = 0; i < nargs; i++) {
	if (args[i].len == VAR_LENGTH_ARG) {
	    arg[i] = (char*) args[i].u.ptr;
	} else if (args[i].len > 4)  {
	    elog(WARN,"arg_length of argument %d too long",i);
	} else {
	    arg[i] = (char*)args[i].u.integer;
	}
    }
    
    /* ----------------
     *	call the postgres function manager
     * ----------------
     */
    retval = (char *)
	fmgr(fnid, arg[0], arg[1], arg[2], arg[3],
	     arg[4], arg[5], arg[6], arg[7]);
    
    /* ----------------
     *	put the result in the buffer the user specified and
     *  return the proper code.
     * ----------------
     */
    if (retval == (char *) NULL)	/* void retval */
	return "0";
    
    if (result_is_int) {
	*result_buf = (int) retval;
    } else {
	memmove(result_buf, retval, result_len); 
    }
    return "G";
}

/* ----------------
 *	PQexec -  Send a query to the POSTGRES backend
 *
 * 	The return value is a string.  
 * 	If 0 or more tuples fetched from the backend, return "P portal-name".
 * 	If a query is does not return tuples, return "C query-command".
 * 	If there is an error: return "E error-message".
 *
 *	Note: if we get a serious error or an elog(WARN), then PQexec never
 *	returns because the system longjmp's back to the main loop.
 * ----------------
 */
char *
PQexec(char *query)
{
    PortalEntry *entry = NULL;
    char *result = NULL;
    
    /* ----------------
     *	create a new portal and put it on top of the portal stack.
     * ----------------
     */
    entry = (PortalEntry *) be_newportal();
    be_portalpush(entry);
    
    /* ----------------
     *	pg_eval_dest will put the query results in a portal which will
     *  end up on the top of the portal stack.
     * ----------------
     */
    pg_eval_dest(query, (char **) NULL, (Oid *) NULL, 0, Local);
    
    /* ----------------
     *	pop the portal off the portal stack and return the
     *  result.  Note if result is null, we return C.
     * ----------------
     */
    entry = (PortalEntry *) be_portalpop();
    result = entry->result;
    if (result == NULL) {
	char *PQE = "Cnull PQexec result";
	result = pstrdup(PQE);
    }
    
    if (result[0] != 'P')
	{
	    /* some successful command was executed,
	       but it's not one where we return the portal name so
	       here we should be sure to clear out the portal 
	       (since the caller has no handle on it)
	       */
	    pbuf_close(entry->name); 
	    
	}
    return result;
}

/* ----------------------------------------------------------------
 *			pqtest support
 * ----------------------------------------------------------------
 */

/* ----------------
 *	pqtest_PQexec takes a text query and returns the number of
 *	tuples it returns.  Note: there is no need to PQclear()
 *	here - the memory will go away at end transaction.
 * ----------------
 */
int
pqtest_PQexec(char *q)
{
    PortalBuffer *a;
    char 	 *res;
    int 	 t;
    
    /* ----------------
     *	execute the postgres query
     * ----------------
     */
    res = PQexec(q);
    
    /* ----------------
     *	return number of tuples in portal or 0 if command returns no tuples.
     * ----------------
     */
    t = 0;
    switch(res[0]) {
    case 'P':
	a = PQparray(&res[1]);
	if (a == NULL)
	    elog(WARN, "pqtest_PQexec: PQparray could not find portal %s",
		 res);
	
	t = PQntuples(a);
	break;
    case 'C':
	break;
    default:
	elog(NOTICE, "pqtest_PQexec: PQexec(%s) returns %s", q, res);
	break;
    }
    
    return t;
}

/* ----------------
 *	utilities for pqtest_PQfn()
 * ----------------
 */
char *
strmake(char *str, int len)
{
    char *newstr;
    if (str == NULL) return NULL;
    if (len <= 0) len = strlen(str);
    
    newstr = (char *) palloc((unsigned) len+1);
    (void) strncpy(newstr, str, len);
    newstr[len] = (char) 0;
    return newstr;
}

#define SKIP 0
#define SCAN 1

static char spacestr[] = " ";

static int
strparse(char *s, char **fields, int *offsets, int maxfields)
{
    int len = strlen(s);
    char *cp = s, *end = cp + len, *ep;
    int parsed = 0;
    int mode = SKIP, i = 0;
    
    if (*(end - 1) == '\n') end--;
    
    for (i=0; i<maxfields; i++)
	fields[i] = spacestr;
    
    i = 0;
    while (!parsed) {
	if (mode == SKIP) {
	    
	    while ((cp < end) &&
		   (*cp == ' ' || *cp == '\t'))
		cp++;
	    if (cp < end) mode = SCAN;
	    else parsed = 1;
	    
	} else {
	    
	    ep = cp;
	    while ((ep < end) && (*ep != ' ' && *ep != '\t'))
		ep++;
	    
	    if (ep < end) mode = SKIP;
	    else parsed = 1;
	    
	    fields[i] = strmake(cp, ep - cp);
	    if (offsets != NULL)
		offsets[i] = cp - s;
	    
	    i++;
	    cp = ep;
	    if (i > maxfields)
		parsed = 1;
	    
	}
    }
    return i;
}

/* ----------------
 *	pqtest_PQfn converts it's string into a PQArgBlock and
 *	calls the specified function, which is assumed to return
 *	an integer value.
 * ----------------
 */
int
pqtest_PQfn(char *q)
{
    int k, j, i, v, f, offsets;
    char *fields[8];
    PQArgBlock pqargs[7];
    int res;
    char *pqres;
    
    /* ----------------
     *	parse q into fields
     * ----------------
     */
    i = strparse(q, fields, &offsets, 8);
    printf("pqtest_PQfn: strparse returns %d fields\n", i); /* debug */
    if (i == 0)
	return -1;
    
    /* ----------------
     *	get the function id
     * ----------------
     */
    f = atoi(fields[0]);
    printf("pqtest_PQfn: func is %d\n", f); /* debug */
    if (f == 0)
	return -1;
    
    /* ----------------
     *	build a PQArgBlock
     * ----------------
     */
    for (j=1; j<i && j<8; j++) {
	k = j-1;
	v = atoi(fields[j]);
	if (v != 0 || (v == 0 && fields[j][0] == '0')) {
	    pqargs[k].len = 4;
	    pqargs[k].u.integer = v;
	    printf("pqtest_PQfn: arg %d is int %d\n", k, v); /* debug */
	} else {
	    pqargs[k].len = VAR_LENGTH_ARG;
	    pqargs[k].u.ptr = (int *) textin(fields[j]);
	    printf("pqtest_PQfn: arg %d is text %s\n", k, fields[j]); /*debug*/
	}
    }
    
    /* ----------------
     *	call PQfn
     * ----------------
     */
    pqres = PQfn(f, &res, 4, 1, pqargs, i-1);
    printf("pqtest_PQfn: pqres is %s\n", pqres); /* debug */
    
    /* ----------------
     *	free memory used
     * ----------------
     */
    for (j=0; j<i; j++) {
	pfree(fields[j]);
	if (pqargs[j].len == VAR_LENGTH_ARG)
	    pfree(pqargs[j].u.ptr);
    }
    
    /* ----------------
     *	return result
     * ----------------
     */
    printf("pqtest_PQfn: res is %d\n", res); /* debugg */
    return res;
}

/* ----------------
 *	pqtest looks at the first character of it's test argument
 *	and decides which of pqtest_PQexec or pqtest_PQfn to call.
 * ----------------
 */
int32
pqtest(struct varlena *vlena)
{
    char 	 *q;
    
    /* ----------------
     *	get the query
     * ----------------
     */
    q = textout(vlena);
    if (q == NULL)
	return -1;
    
    switch(q[0]) {
    case '%':
	return pqtest_PQfn(&q[1]);
	break;
    default:
	return pqtest_PQexec(q);
	break;
    }
    return(0);
}
